The spine is susceptible to various medical conditions that reduce the area within the vertebra available for the spinal cord and nerve roots. For instance, spinal stenosis is a condition in which the spinal canal narrows and compresses the spinal cord and nerve roots. Spinal stenosis may be caused by many medical conditions, such as the calcification and thickening of the ligaments of the spine (e.g., from deposits of calcium salts), enlargement of bones and joints, formation of osteophytes (bone spurs), a herniated (bulging) disk, and diseased bone or tumors may result in an ingrowth into the spinal cord area. Thus, the amount of anatomical space available for the spinal cord and nerve roots that emanate from the spinal cord can be reduced, which often results in lower back pain as well as pain or abnormal sensations in the extremities. Spinal stenosis may affect the cervical, thoracic or lumbar spine.
Surgical procedures are available for treating spinal stenosis by relieving pressure on the spinal cord through posterior arch expansion. The conventional surgical procedures typically involve first making an incision in the back and stripping muscles and supporting structures away from the spine to expose the posterior portion of the vertebral column. Once exposed, the spinal canal may be widened (i.e. the posterior arch may be expanded), either by removing the lamina (laminectomy) or by cutting the lamina and then spreading it apart with an implant (laminoplasty). The invasive nature of conventional posterior arch expansion methods often result in significant post-operative pain and long patient recovery times.